The invention relates to a bale opener for removing fiber tufts from fiber bales such as cotton bales or chemical fiber bales, by means of a detaching device comprising, for example, a rapidly rotating detaching (opening) roll. The detaching device is accommodated in a downwardly open housing which is mounted in a cantilever fashion on a bale opener tower which itself is mounted on a carriage travelling back and forth along fiber bales arranged in a series. The cantilevered detaching device may be vertically moved relative to the tower by means of a lifting motor or the like.
In a known apparatus a friction wheel is secured to the carriage and the friction wheel rolls on a stationarily fixed, horizontally oriented fiber tuft suction channel. A counting disc with slit openings is coaxially mounted on the shaft of the friction wheel and two stationary inductive sensors are associated with the zone where the slit openings are provided for sensing the number of revolutions of the friction wheel. An evaluating device which processes the pulses emitted by the sensor, determines the location of the bale opener along its travel path. A positive connection between the friction wheel and the upper face of the channel is, among others, dependent from the pressing force and the coefficient of friction. In case the upper face (frictional contact surface) of the channel is exposed to slippery material such a brake fluid or the pressing force is varied, slippage of the friction wheel relative to the frictional surface may occur. Such an occurrence would result in a faulty indication of the actual position of the bale opener along its travelling path. It is a further disadvantage of known constructions of the above-outlined type that the cooperation between the sensors and the counting disc may be adversely affected. In particular, the setting between sensors and the counting disc may be mechanically disturbed.